The direct effects of troglitazone on rat mesangial cells under conditions which mimic type II diabetes mellitus in vitro.

摘要

Our laboratory has shown that troglitazone (TRO), a thiazolidinedione and PPAR γ agonist, prevents mesangial expansion and glomerulosclerosis in diabetic rats. We hypothesized that TRO would have a direct effect on rat mesangial cells (RMC) grown in vitro under certain conditions mimicking type II diabetes mellitus. To test this hypothesis we evaluated the effects of TRO directly on rat mesangial cells by growing them in medium containing 5 mM glucose, 30 mM glucose, or 25 mM mannitol & 5 mM glucose (Hyperglycemia), 25 μM or 100 M linoleic or oleic acid (Dyslipidemia), or hyperglycemic or dyslipidemic states in the presence of TGF-γ or PDGF-BB (Growth Factors). The cultures were either left untreated (UNT), treated with 10 μM TRO, or 100 μM clofibrate (CLO). The following parameters were used to assess mesangial cell responses: detection of PPAR-γ and-α mRNA, the degree of PPAR-γ & -α transcriptional activation by PPRE/luciferase assay, spread cell area, total protein production, laminin production, type I collagen production, and matrix metalloproteinase activity (MMP). TRO has a direct effect on RMC grown in vitro under certain conditions mimicking type II diabetes mellitus. These effects seem to be mediated by TRO through the PPAR-γ signaling pathway, which is in place and active in RMC in vitro. The direct effect of TRO treatment on rat mesangial cells in vitro is illustrated by (1) the decrease in spread cell area, (2) activation of PPAR transcriptional activity, (3) the consistent decrease in laminin production, (4) changes in type I collagen production, and (5) inhibition of MMP activity. Of the greatest importance is the observation that TRO may influence production/deposition of a pathological fibrotic connective tissue matrix by these cells without changing the normal expression of mesangial matrix components in vivo under similar conditions.